This page was written in 1997 when Karsten Albe was still working
on his PhD thesis

Computer Simulation and Boron Nitride

Karsten Albe

Motivation

Cubic boron nitride (c-BN) is of considerable
interest in materials science due to its extraordinary properties, such
as extreme hardness, chemical inertness, high melting temperature, wide
band gap and low dielectric constant. Nowadays, thin film deposition of
c-BN is successfully done by PVD methods, but the problems appearing here
are manifold and the processes which are relevant for growth and stability
of BN-films are hardly understood. For this reason computer simulation
on atomic scale is a helpful tool for process development.

Methods

The methods in use range from dynamical TRIM-simulations
to most accurate quantum chemical codes. Full self-consistent first
principles calculations, which are based on density functional theory,
are done for characterization of materials properties, like elastic constants,
cohesive energies and defect energies. A pseudopotential code with plane
wave basis as well as a LCAO code with local and nonlocal corrections are
applied. The simulation of detail processes during the thin film growth
is done by Molecular Dynamics calculations, which are possible by
a new interatomic potential. This empirical bond order potential
was recently developed for MD-calculations of different solid BN-modifications
and molecular BxNy species.

Applications

The desired cubic BN modification grows typically
on a hexagonal BN layer. The influence of impacting N2 and Ar
projectiles is studied by MD-simulations. The left picture shows N atoms
between vertically oriented BN layers , the right picture the influence
of an Ar impact on horizontally oriented layers.

Computer simulation studies can be helpful to identify new configurations:
Structures of two hypthetical fullerenes, B12N12
, B28N28, calculated by the empirical interatomic
potential: